The development of the controller for the machine needs to reach the requirements of high velocity, high accuracy and the high-quality cutting surface. For meeting the above requirements, the controller using the controlling method of acceleration and deceleration before interpolating is developed, which is able to decrease the contouring error caused by the controlling method of acceleration and deceleration after interpolating. However, for achieving the motion control using the method of acceleration and deceleration before interpolating, the controller has to preview and analyze the processing pathway to decide the location for acceleration or deceleration and the velocity distribution in the processing pathway, to be the basis of the interpolating for the motion control.
In the prior arts, there are two commonly used estimating methods. One estimating method is the velocity difference estimating method in the U.S. Pat. No. 4,757,457, which uses the velocity difference caused by each axle of the machine passing through two adjacent blocks in a corner to be the basis of the limitation for the processing velocity in the corner. However, this method is easy to cause the over speed situation in the processing pathway formed by successive blocks. The other estimating method is the triangle difference estimating method, which uses the angle formed by two adjacent blocks where the machine passing through and the parameter of the server circuit to be the basis of the limitation for the processing velocity in the corner. This method is also easy to cause the over speed situation in the processing pathway formed by successive blocks.
Therefore, how to find the portions having steep orientation variations in the processing pathway and how to control the acceleration and deceleration appropriately so as to prevent the machine from exceeding the acceleration and deceleration property of the server are important. Under such background, it is necessary to develop a simple algorithm to calculate the limitation for the processing velocity of each block end in the corner of the processing pathway.
In order to overcome the drawbacks in the prior art, an accumulative method for estimating the velocity limitation is provided. The particular design in the present invention not only solves the problems described above, but also is easy to be implemented. Thus, the invention has the utility for the industry.